Liquid spray dispensers of various types are well known in the art. Many of these dispensers are of the aerosol variety wherein a precharged gaseous propellant is used to pressurize the contents of the package and produce a spray when an actuating means is triggered by the end user. Typical applications for such dispensers include spray paints, deodorants, hair sprays, adhesives, disinfectants and the like.
Because the conditions of use may vary widely for a given product, e.g., as in the application of a spray glue to either a large surface for overall bonding or to only a small portion of a surface for localized bonding, it has been found desirable on some such applications to provide aerosol packages having more than a single discharge orifice capable of altering the spray pattern for the material being dispensed. This allows the user to select whatever spray pattern best suits his or her needs in any given circumstance by simply rotating the discharge nozzle on the package from one orifice to another. One example of a package of this general type is disclosed in U.S. Pat. No. 3,083,872 issued to Meshberg on Apr. 2, 1963.
Unfortunately, the use of an aerosol propellant to dispense a liquid spray can give rise to material compatibility problems between the liquid being dispensed and the propellant. In addition, pressurization of the dispensing package can increase the cost of manufacture and possibly contribute to environmental problems due to escape of the propellant to the atmosphere either during dispensing of the liquid product or upon disposal of the package.
Accordingly, there has been significant effort devoted toward development of liquid spray dispensing packages which do not require the use of an aerosol propellant and which can be pressurized by the user during the dispensing cycle. The most typical approach has been to employ a positive displacement liquid pump within the dispensing package. The pump is capable of being manually actuated by manipulation with by the user's index finger.
Pump spray dispensing packages employing multiple spray orifices are also known. An exemplary package of this type is disclosed in 1987 Japanese Utility Model No. Showa 62-38766 in the names of Kishi and Goto and filed by Yoshino Kogyosho Co., Ltd. While the positive displacement pump approach has done much to solve the material compatibility and environmental concerns associated with aerosol packages, it has been found that the use of more than a single dispensing orifice in a manually pressurized spray dispensing pump can give rise to underwetting or overwetting problems when the user moves the nozzle from one orifice to another, particularly if the user fully depresses the pump actuating means for each stroke of the pump. It is believed that these underwetting/overwetting problems are more pronounced with packages employing manually actuated pumps because, unlike aerosol packages, users tend to hold a pump package in a substantially fixed position for each stroke of the pump and then move the package from one position to the next between pump strokes.
The aforementioned difficulties are most apparent in applications such as hair spray, where the user may want a broad spray pattern for overall treatment of their hair, but only a very narrow spray pattern to produce styling highlights. If the orifice designed to produce a very narrow spray pattern for styling highlights delivers the same total amount of product that is used for overall treatment of the user's hair on each pump stroke, there will be a strong tendency to overwet the portion of the user's hair being spot treated. Conversely, if the package is designed to optimize the amount of product to be delivered during spot treatment, the amount of product delivered on each full pump stroke will most likely be too low when the user selects the broad spray pattern for overall treatment of their hair. This will, in most instances, result in underwetting.
The prior art solution to overwetting/underwetting problems of the aforementioned type in multiple orifice packages employing manually actuated pumps has been to employ a single maximum pump stroke which is a compromise between the extremes required by the different spray orifices, resulting in a liquid application amount per unit of area being treated which is not completely satisfactory for any of the spray orifices.